Skinceuticals C E Ferulic Serum leads with proven results on fine lines and environmental protection per its long history, while Drunk Elephant C Firma Fresh Day Serum provides strong value at $78 versus $185. Both deliver 15% L-ascorbic acid with ferulic acid and vitamin E, but Skinceuticals' ready-to-use format and 2005 release give it an edge in established efficacy. Drunk Elephant wins on a...